This invention relates to a method for the removal of organic vapor from a gas containing organic vapor and the recovery of the removed vapor.
Volatile organic solvents, e.g., perchloroethylene and 1,1,1-trichloroethane, are employed in a variety of applications such as dry cleaning and as a component in various coating and adhesive compositions. Due to the expense of such solvents and the potential hazards often attributed to the solvents, particularly the vapors thereof, it is generally desirable to remove the solvent vapors prior to the release of a gas containing said vapors to the atmosphere and to recover the solvent for reuse.
In one method employed heretofore for recovering the solvent vapor, the gas containing the vapors is cooled to a temperature sufficient to condense the solvent vapor. Unfortunately, since the concentration of the solvent is generally relatively low, e.g., air exiting from a dry cleaning unit often contains as little as 50 parts per million of the dry cleaning solvent (generally methylene chloride), extensive amounts of energy are required to recover the solvent.
In another prior art method for recovering the volatile solvent, the vapor laden gas is contacted with a bed of activated carbon or other particulate absorbent. Unfortunately, since the activated charcoal does not rapidly absorb the organic vapor, a relatively large bed or column is required to effectively remove the solvent vapor from the air, thereby necessitating a large outlay of capital, time and energy.
In view of these deficiencies of the prior art, it remains highly desirable to provide an economical and effective method for separating organic vapor from a gas containing said vapor and for subsequently recovering the organic material in a liquid form.